This invention relates to a conveyor stub idler roll apparatus and particularly to a stub roll for edge support of the return run of an endless flexible sidewall conveyor belt handling particulate matter.
The movement of industrial products in the form of particulate and fibrous materials has for years been conveniently done with trough-type belt conveyors operating horizontally or at inclines to 20 degrees. The conveyor consists of a middle support structure with two or three roll inclined rollers (idlers) located every four to five feet along the top or "carrying side" of the frame in order to form the belt into a trough. Although the trough shaped belt structure provides a substantial confinement of the material, there is some movement of the material from the belt, particularly in inclined attitudes, caused by the belt as it impacts on the individual idler rolls. The operating environment of these conveyors range from clean environments such as food plant installations to extremely dirty environments such as foundries, coal handling systems, paper mills and the like. The majority of these conveyors are located outside and are virtually unprotected from the elements.
Belt speeds range from 150 Ft./min. to 500 Ft./min, and faster, which subjects the idler bearings and drive system to relatively severe operating conditions. Idler bearings must be periodically lubricated in order to insure that the rollers turn and prevent belt damage. Of equal importance, however, the lubricant is required to purge the bearing seals of foreign matter caused by the congealing of the grease as it cools when the conveyor is shut down, drawing in the dirt to the bearing surfaces.
In 1968, a new type of conveyor belt was introduced to the public, incorporating a flat belt with corrugated sidewalls and cleats secured to the top of the belt, which formed pockets in the conveyor belt. With this design, conveyors were now capable of running horizontally, turning up at steep angles (to 90 degrees or vertical) then turning once more to the horizontal position to discharge. These belts were supported by flat idlers on the carrying side because flexible sidewall belting is designed with a transverse truss ply so that it cannot trough. This is essential to the belts ability to be able to be formed into an "L" or "Z" shaped conveyor. Likewise, conventional flat idlers on the carrying side and conventional flat return rolls running on the flexible sidewalls were employed on the return side.
After a number of years of using the conventional style return roll for this type of belt, it became apparent that the conventional return roll caused excessive wear to sidewalls which led to cracking, belt mis-alignment, and premature failure. In the early 1980's, stub idlers were introduced for use in place of the return roll. These stub idlers were cantilevered rollers which run on the outboard extension of the base belt, thereby allowing the sidewalls to hang free on the return side of the belt. However, all of these units were manufactured in the same way as the conventional return idler with the bearings mounted in the roller. Because of the added load due to the cantilevered design, the shafts could not be drilled in order to afford a channel for the lubrication of the bearings. Consequently, all of the idlers were provided as "sealed for life". In addition, the standard support bracket was used, which provides no lateral adjustment in order to maintain the proper gap between the sidewall and the end of the roller, which is necessary to prevent sidewall wear and damage.
Various prior art variations of this structure are used in industry and variations are shown in the prior art. For example, reference may be made to any of the following U.S. issued patents:
______________________________________ U.S. Pat. No. Issue Date Inventor ______________________________________ 1,062,325 05-20-1913 Dierdorff 1,924,807 08-29-1933 Sayers 3,207,291 09-21-1965 Barnish 3,334,727 08-08-1967 Rieser 3,420,590 01-07-1969 Bilocq 3,604,766 08-14-1969 Bankauf 4,438,617 03-27-1984 Ulrich et al ______________________________________
However, the above patents generally disclose idlers designed for the troughing or "carrying side" of the belt and/or attachments to the carrying side idler to prevent mis-alignment.
Notwithstanding, the significant development in the art and the different rollers commercially available, the standard stub roller for the return run of the sidewall belt continues to be a significant maintenance problem and cost. This is particularly significant because idler failure causes the shutdown of the conveyor (and the costly loss of product processing) as well as damage to the expensing belt itself. There is, therefore, a continuing demand for an improved idler roll design in the area of stub idlers for the rapidly expanding field of flexible sidewall conveyor belt applications.